I understand your point (and agree with it), but who would own them if not corporations? A hippy commune?
(and there are at least 2 TV news sources, the only 2 I ever watch, that are owned by governments....so I suppose that's an option as well)
I am fine with private firms (or worker co-ops!) controlling most of the mass media provided that alternative means for information to flow are available, academic freedom is well-respected, and some portion of the media is state-run so as to prioritize social utility over profit. It would be nice for private, public, scholarly, and popular media sources to coexist - all supplementing, challenging, and policing one another to provide people a rich array of at least somewhat accountable choices.
Unfortunately, the presense of biases is virtually inevitable and something we have to cope with.